The background of this invention will be described as it relates to the filtering of paint, although it will be understood from the disclosure to follow that the invention is also applicable to the filtering of other materials.
When professional painters use an airless spray gun, they first filter or strain the paint so it will not clog the tiny nozzle in the spray gun.
Typically, the do-it-yourself user of an airless spray gun bought at the local hardware store is not even aware that paint should be filtered before use. As a result, an airless spray gun is often clogged after a single use, after the paint in it has dried; and the spray gun cannot be reused unless a new nozzle is purchased and installed.
The present invention is a system that professional painters or do-it-yourself painters can use to strain or filter paint prior to using the paint in an airless spray gun. In the prior art, professional painters have typically filtered paint prior to using the spray equipment, by first placing a tapered filter cloth inside an empty paint bucket. The painter then pours the paint into the interior of the filter cloth so that the paint passes through the pores in the filter cloth to strain the paint. Since the prior art filter cloth is tapered generally to the shape of the paint bucket and extends down to near the bottom of the bucket, the painter must pour the paint into the bucket and then raise the filter cloth to ensure that all the paint passes through the cloth and into the bucket. This job is inconvenient, messy, tedious, and places a strain on the painter's back when constantly filtering paint in this manner. The filter cloth is often pulled into the bucket by the weight of the paint, and consequently, unfiltered paint will spill into the bucket, slowing down the filtering process. The tapered bottom of the conventional filter cloth also can tend to cause paint to clog the bottom of the filter cloth, which also slows down the filtering process. When the painter pulls the filter cloth upwardly out of the bucket, the clogged bottom portion adds to the weight of the filter, placing a strain on the back of the painter who must hold the filtering cloth over the bucket until all paint has finally passed through it.
Several prior art patents are directed to solving some of the problems that have persisted in the conventional procedure for filtering paint. U.S. Pat. No. 4,025,436 to Shea discloses a large frame for holding a tapered filter cloth over the top of a paint bucket. U.S. Pat. No. 2,883,057 to Richards discloses a paint strainer in the form of a conical funnel with a wire mesh screen mounted in the top of the funnel. The funnel is supported on the top of the paint bucket by a wire rod attachment. Other strainers are disclosed in U.S. Pat. No. 508,175 to Leggett and 484,459 to Reynolds. These patents disclose wire rod supports for holding a filtering cloth or wire mesh screen over the top of a paint bucket.
The prior art approaches to improving paint filtering allow the painter to pour the paint through a supported filter without requiring the painter to hold the filter cloth above the container until all the paint drips through the cloth. However, these devices have several disadvantages. They require special, relatively expensive filtering devices. They tend to be bulky, heavy and awkward to use. They can require extra time for assembling parts of the filtering assembly. They can be messy to use, and are not easily stored when not in use. In addition, they do not prevent debris or other foreign particles from entering into the paint during the filtering process. Moreover, they leave the top surface of the paint exposed to the environment, and this can cause the top of the paint to skin over rather quickly, especially during hot weather. The prior art devices also are not adapted to facilitate more inexpensive mass production techniques.
The present invention solves the problems that result from the common prior art practice of filtering paint by pouring it through the tapered filtering cloth and then raising the cloth up through the filtered paint. In addition, the present invention overcomes problems not solved by the improvements described in the prior art patents referred to above.